A cast steel strong back is fitted in way of the combustion space to help absorb （）.
举一反三
- Steel is not as _____ as cast iron; it does not break as easily.
- At the top of the A-frames there is a strong cast iron frame called （）.
- The cylinder is fitted with internal liner so that a water space is left （） the liner and the outer wall.
- （） of the A-frames there is a strong cast iron frame called the scavenging air box.
- On top of scavenging air box is mounted a strong cast iron frame for each cylinder known as（）